Moisture resistant coating for barrier films

ABSTRACT

A barrier film having a substrate, a base polymer layer applied to the substrate, an oxide layer applied to the base polymer layer, and a top coat polymer layer applied to the oxide layer. An optional inorganic layer can be applied over the top coat polymer layer. The top coat polymer includes a silane and an acrylate co-deposited to form the top coat layer. The use of a silane co-deposited with an acrylate to form the top coat layer of the barrier films provide for enhanced resistance to moisture and improved peel strength adhesion of the top coat layer to the underlying barrier stack layers.

REFERENCE TO RELATED APPLICATION

The present application, which is a continuation of U.S. patentapplication Ser. No. 12/829535, filed on Jul. 2, 2010, is related toU.S. Patent Publication Number 2012/0003451 (Weigel et al.) which ishereby incorporated herein by reference as if fully set forth.

BACKGROUND

Multilayer stacks of polymers and oxides are deposited in a single passcoating process on flexible plastic films to make high barrier filmsresistant to moisture permeation. Examples of these barrier films aredescribed in U.S. Pat. Nos. 5,440,446; 5,877,895; and 6,010,751, all ofwhich are incorporated herein by reference as if fully set forth. Thesehigh barrier films have a number of applications in the display,lighting, and solar markets as flexible replacements for glassencapsulating materials. However, under certain conditions multilayerstacks of polymers and oxides may suffer degradation in adhesionperformance after extended exposure to moisture, possibly causing thesehigh barrier stacks to delaminate at the oxide-polymer interface andcausing the flexible plastic film to detach from the device.

One solution to this problem is to use what is referred to as a “tie”layer of particular elements such chromium, zirconium, titanium, siliconand the like, which are often sputter deposited as a mono- or thin-layerof the material either as the element or in the presence of small amountof oxygen. The tie layer element can then form chemical bonds to boththe substrate layer, an oxide, and the capping layer, a polymer.

Tie layers are generally used in the vacuum coating industry to achieveadhesion between layers of differing materials. The process used todeposit the layers often requires fine tuning to achieve the right layerconcentration of tie layer atoms. The deposition can be affected byslight variations in the vacuum coating process such as fluctuation invacuum pressure, out-gassing, and cross contamination from otherprocesses resulting in variation of adhesion levels in the product. Inaddition, tie layers often do not retain their initial adhesion levelsafter exposure to water vapor. A more robust solution for adhesionimprovement in barrier films is desirable.

SUMMARY

A barrier film, consistent with the present invention, includes asubstrate, a base polymer layer applied to the substrate, an oxide layerapplied to the base polymer layer, and a top coat polymer layer appliedto the oxide layer. The top coat polymer includes a silane and anacrylate co-deposited to form the top coat layer. An optional inorganiclayer can be applied over the top coat polymer layer.

A process for making a barrier film, consistent with the presentinvention, includes the steps of providing a substrate, applying a basepolymer layer to the substrate, applying an oxide layer to the basepolymer layer, and co-depositing a silane and an acrylate to form a topcoat polymer layer on the oxide layer.

The use of a silane co-deposited with an acrylate to form the top coatlayer of the barrier film provides for enhanced resistance to moistureand improved peel strength adhesion of the top coat layer to theunderlying barrier stack layers.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are incorporated in and constitute a part ofthis specification and, together with the description, explain theadvantages and principles of the invention. In the drawings,

FIG. 1 is a diagram of a barrier film having a moisture resistantcoating; and

FIG. 2 is a diagram illustrating a process for making a barrier film.

DETAILED DESCRIPTION

FIG. 1 is a diagram of a barrier film 10 having a moisture resistantcoating. Film 10 includes layers arranged in the following order: asubstrate 12; a base polymer layer 14; an inorganic layer 16; a top coatpolymer layer 18; and an optional inorganic layer 20. Base polymer layer14 and inorganic layer 16 together form a dyad and, although only onedyad is shown, film 10 can include additional alternating layers of basepolymer and oxide between substrate 10 and top coat polymer layer 18. Asilane is co-deposited with an acrylate to form top coat polymer layer18, which improves the moisture resistance of film 10 and the peelstrength adhesion of top coat polymer layer 18 to the underlying barrierstack layers, as explained below. Materials for the layers of barrierfilm 10 are identified in the Examples.

Volatilizable acrylate and methacrylate monomers are useful for formingthe base and top coat polymer layers. In some embodiments, volatilizableacrylates are used. Volatilizable acrylate and methacrylate monomers mayhave a molecular weight in the range from about 150 to about 600 gramsper mole, or, in some embodiments, from about 200 to about 400 grams permole. In some embodiments, volatilizable acrylate and methacrylatemonomers have a value of the ratio of the molecular weight to the numberof (meth)acrylate functional groups per molecule in the range from about150 to about 600 g/mole/(meth)acrylate group, in some embodiments, fromabout 200 to about 400 g/mole/(meth)acrylate group. Fluorinatedacrylates and methacrylates can be used at higher molecular weightranges or ratios, for example, about 400 to about 3000 molecular weightor about 400 to about 3000 g/mole/(meth)acrylate group. Exemplary usefulvolatilizable acrylates and methacrylates include hexanediol diacrylate,ethoxyethyl acrylate, phenoxyethyl acrylate, cyanoethyl (mono)acrylate,isobornyl acrylate, isobornyl methacrylate, octadecyl acrylate, isodecylacrylate, lauryl acrylate, beta-carboxyethyl acrylate,tetrahydrofurfuryl acrylate, dinitrile acrylate, pentafluorophenylacrylate, nitrophenyl acrylate, 2-phenoxyethyl acrylate, 2-phenoxyethylmethacrylate, 2,2,2-trifluoromethyl (meth)acrylate, diethylene glycoldiacrylate, triethylene glycol diacrylate, triethylene glycoldimethacrylate, tripropylene glycol diacrylate, tetraethylene glycoldiacrylate, neopentyl glycol diacrylate, propoxylated neopentyl glycoldiacrylate, polyethylene glycol diacrylate, tetraethylene glycoldiacrylate, bisphenol A epoxy diacrylate, 1,6-hexanediol dimethacrylate,trimethylol propane triacrylate, ethoxylated trimethylol propanetriacrylate, propylated trimethylol propane triacrylate,tris(2-hydroxyethyl)isocyanurate triacrylate, pentaerythritoltriacrylate, phenylthioethyl acrylate, naphthloxyethyl acrylate, cyclicdiacrylates (for example, EB-130 from Cytec Industries Inc. andtricyclodecane dimethanol diacrylate, available as SR833S from SartomerCo.), epoxy acrylate RDX80095 from Cytec Industries Inc., and mixturesthereof.

Useful monomers for forming the base and top coat polymer layers areavailable from a variety of commercial sources and include urethaneacrylates (e.g., available from Sartomer Co., Exton, Pa. under the tradedesignations “CN-968” and “CN-983”), isobornyl acrylate (e.g., availablefrom Sartomer Co. under the trade designation “SR-506”),dipentaerythritol pentaacrylates (e.g., available from Sartomer Co.under the trade designation “SR-399”), epoxy acrylates blended withstyrene (e.g., available from Sartomer Co. under the trade designation“CN-120S80”), di-trimethylolpropane tetraacrylates (e.g., available fromSartomer Co. under the trade designation “SR-355”), diethylene glycoldiacrylates (e.g., available from Sartomer Co. under the tradedesignation “SR-230”), 1,3-butylene glycol diacrylate (e.g., availablefrom Sartomer Co. under the trade designation “SR-212”), pentaacrylateesters (e.g., available from Sartomer Co. under the trade designation“SR-9041”), pentaerythritol tetraacrylates (e.g., available fromSartomer Co. under the trade designation “SR-295”), pentaerythritoltriacrylates (e.g., available from Sartomer Co. under the tradedesignation “SR-444”), ethoxylated (3) trimethylolpropane triacrylates(e.g., available from Sartomer Co. under the trade designation“SR-454”), ethoxylated (3) trimethylolpropane triacrylates (e.g.,available from Sartomer Co. under the trade designation “SR-454HP”),alkoxylated trifunctional acrylate esters (e.g., available from SartomerCo. under the trade designation “SR-9008”), dipropylene glycoldiacrylates (e.g., available from Sartomer Co. under the tradedesignation “SR-508”), neopentyl glycol diacrylates (e.g., availablefrom Sartomer Co. under the trade designation “SR-247”), ethoxylated (4)bisphenol a dimethacrylates (e.g., available from Sartomer Co. under thetrade designation “CD-450”), cyclohexane dimethanol diacrylate esters(e.g., available from Sartomer Co. under the trade designation“CD-406”), isobornyl methacrylate (e.g., available from Sartomer Co.under the trade designation “SR-423”), cyclic diacrylates (e.g.,available from UCB Chemical, Smyrna, Ga., under the trade designation“IRR-214”) and tris (2-hydroxy ethyl) isocyanurate triacrylate (e.g.,available from Sartomer Co. under the trade designation “SR-368”),acrylates of the foregoing methacrylates and methacrylates of theforegoing acrylates.

In some embodiments, one of the polymer layers (e.g., the top coatpolymer layer) in the barrier film can be formed from co-depositing asilane (e.g., an amino silane or cyclic aza-silane) and aradiation-curable monomer (e.g., any of the acrylates listed above).Co-depositing includes co-evaporating and evaporating a mixture of thesilane and the monomer. Cyclic aza-silanes are ring compounds, whereinat least one of the ring members is a nitrogen and at least one of thering members is a silicon, and wherein the ring contains at least onenitrogen-to-silicon bond. In some embodiments, the cyclic aza-silane isrepresented by the general formula

In other embodiments, the cyclic aza-silane is represented by thegeneral formula

In either of these embodiments, each R is independent alkyl having up to12, 6, 4, 3, or 2 carbon atoms and R′ is hydrogen, alkyl, or alkenylwith alkyl and alkenyl each having up to 12, 6, 4, 3, or 2 carbon atomsand optionally substituted by amino. Exemplary cyclic aza-silanesinclude 2,2-dimethoxy-N-butyl-1-aza-2-silacyclopentane,2-methyl-2-methoxy-N-(2-aminoethyl)-1-aza-2-silacyclopentane,2,2-diethoxy-N-(2-aminoethyl)-1-aza-2-silacyclopentane,2,2-dimethyl-N-allyl-1-aza-2-silacyclopentane,2,2-dimethoxy-N-methyl-1-aza-2-silacyclopentane,2,2-diethoxy-1-aza-2-silacyclopentane,2,2-dimethoxy-1,6-diaza-2-silacyclooctane, andN-methyl-1-aza-2,2,4-trimethylsilacyclopentane. When the cyclicaza-silane is placed in the presence of a hydroxyl (e.g., silanol) groupit quickly reacts to form a Si—O—Si (siloxane) linkage from the oxidesurface to the co-condensed pre-polymer while the nitrogen moietybecomes a reactive amine on the other end of the molecule that can bondwith pre-polymer compound(s) during polymerization. Amino silanes, whichhave the general formula Z₂N-L-SiY_(x)Y′_(3-x), wherein each Z isindependently hydrogen or alkyl having up to 12 carbon atoms, L isalkylene having up to 12 carbon atoms, Y is a hydrolysable group (e.g.,alkoxy having up to 12 carbon atoms or halogen), and Y′ is anon-hydrolysable group (e.g., alkyl having up to 12 carbon atoms) havesilane groups capable of forming siloxane bond with a metal oxidesurface and amino groups capable of reacting with polymerizablecompounds (e.g., acrylates). Exemplary amino silanes include (e.g.,3-aminopropyltrimethoxysilane; 3-aminopropyltriethoxysilane;3-(2-aminoethyl)aminopropyltrimethoxysilane;N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane,bis-(gamma-triethoxysilylpropyl)amine;N-(2-aminoethyl)-3-aminopropyltributoxysilane;6-(aminohexylaminopropyl)trimethoxysilane; 4-aminobutyltrimethoxysilane;4-aminobutyltriethoxysilane;3-aminopropyltris(methoxyethoxyethoxy)silane;3-aminopropylmethyldiethoxysilane;3-(N-methylamino)propyltrimethoxysilane;N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane;N-(2-aminoethyl)-3-aminopropylmethyldiethoxysilane;N-(2-aminoethyl)-3-aminopropyltrimethoxysilane;N-(2-aminoethyl)-3-aminopropyltriethoxysilane;3-aminopropylmethyldiethoxysilane; 3-aminopropylmethyldimethoxysilane;3-aminopropyldimethylmethoxysilane; and3-aminopropyldimethylethoxysilane). Accordingly, in some embodiments,the barrier film comprises an inorganic layer that shares a chemicalbond (e.g., a siloxane bond) with one or more organic layers. Forexample, a hydroxyl group derived from a metal oxide can react with asilane group on an amino silane or cyclic aza-silane. The amount ofwater vapor present in a multi-process vacuum chamber, for example, canbe controlled to promote the formation of such hydroxyl groups in highenough surface concentration to provide increased bonding sites. Withresidual gas monitoring and the use of water vapor sources, for example,the amount of water vapor in a vacuum chamber can be controlled toensure adequate generation of hydroxyl (e.g., Si—OH) groups.

FIG. 2 is a diagram of a system 22, illustrating a process for makingbarrier film 10. System 22 is contained within an inert environment andincludes a chilled drum 24 for receiving and moving substrate 10 asrepresented by a film 26 providing a moving web. An evaporator 28applies a base polymer, which is cured by curing unit 30 to form basepolymer layer 14 as drum 24 advances the film in a direction shown byarrow 25. An oxide sputter unit 32 applies an oxide to form layer 16 asdrum 24 advances film 26. For additional alternating layers of basepolymer and oxide, drum 24 can rotate in a reverse direction oppositearrow 25 and then advance film 26 again to apply the additionalalternating base polymer and oxide layers, and that sub-process can berepeated for as many alternating layers as desired or needed. Once thealternating layers of base polymer and oxide are complete, drum 24further advances the film, and an evaporator 34 deposits a silane andevaporator 36 deposits an acrylate. The silane and acrylate areco-deposited and, as drum 24 advances the film, are cured together bycuring unit 38 to form top coat polymer 18. Co-depositing the silane andacrylate can involve co-evaporating the materials or evaporating amixture of the materials. As an alternative to an acrylate, a radiationcured monomer can be used with the silane to form the top coat. Thelayers in FIG. 2 are shown separated for illustrative purposes only; thelayers are deposited on one another in the process of making the barrierfilm. Also, each evaporator would be coupled with a source of thecorresponding material to be deposited. The Examples describe in moredetail processes using system 22 to make barrier film 10.

The following explains the advantages of using silane in barrier film 10to form the top coat polymer layer. Silanes are well known in thecoating industry to improve adhesion levels between polymer to glasssurfaces or to greatly alter surface chemistry, in general, ranging fromhydrophilic to hydrophobic. The use of silanes in vapor coatingapplications has been hindered by the high molecular weights oftraditional silane coupling agent compounds. In addition, thehydroxylation step to activate the silane coupling agent to bond to asurface containing hydroxyl groups has hindered their applicability invapor coating processes. The development of cyclic aza-silanes hasenabled vapor process-able silane coupling agent chemistry by reducingmolecular weight thus increasing vapor pressure of the coupling agentmolecule and by removing the hydrolyzing step of the silane couplingagent since cyclic aza-silanes react directly with a silanol surface.

Cyclic aza-silanes are ringed compounds that contain a silicon atom inthe ring bonded to a nitrogen also in the ring. When the cyclicaza-silane is placed in the presence of a hydroxyl (silanol) group itquickly reacts to form a Si—O—Si—R linkage from the oxide surface to theco-condensed pre-polymer while the nitrogen moiety becomes a reactiveamine on the other end of the molecule that can bond with pre-polymercompound(s) during polymerization. While the basic cyclic aza-silanechemistry is known, its implementation in the present vapor coatingprocess is not. Another element in the present process is the ability toform hydroxyl silanol (Si—OH) groups on a freshly sputter deposited SiO₂layer. The amount of water vapor present in a multi-process vacuumchamber can be controlled sufficiently to promote the formation of Si—OHgroups in high enough surface concentration to provide increased bondingsites. With residual gas monitoring and the use of water vapor sources,the amount of water vapor in a vacuum chamber can be controlled toensure adequate generation of Si—OH groups.

This process improves the overall adhesion and adhesion retention ofvapor deposited multilayer barrier coatings after exposure to moistureby the addition of a cyclic aza-silane coupling agent. The cyclicaza-silane coupling agent is added to a pre-polymer formulation andco-evaporated in a vapor coating process where the cyclic aza-silanepre-polymer formulation condenses onto a moving web substrate that hasjust been sputter coated with an oxide of silicon and aluminum. Thecondensed liquid is then polymerized in the same process by electronbeam radiation. With the addition of cyclic aza-silane the peel strengthof the coating is greatly improved and peel strength adhesion isretained after exposure to high heat and humidity conditions.Additionally, the addition of cyclic aza-silane removes the need for atie layer, which greatly simplifies the coating process and barriercoating stack construction by removing the tie layer altogether. Theresulting barrier coatings retain high barrier properties and opticaltransmission performance.

EXAMPLES

All parts, percentages, and ratios in the examples are by weight, unlessnoted otherwise. Solvents and other reagents used were obtained fromSigma-Aldrich Chemical Company; Milwaukee, Wis. unless specifieddifferently.

Materials

90% Si/10% Al targets were obtained from Academy Precision MaterialsInc., Albuquerque, N. Mex.

99.999% Si targets were obtained from Academy Precision Materials Inc.,Albuquerque, N. Mex.

ETFE film: ethylene-tetrafluoroethylene film available from St. GobainPerformance Plastics, Wayne, N.J. under the trade name “NORTON® ETFE.”

ETIMEX® 496.10: EVA film VISTASOLAR® available from ETIMEX Solar GmbH, asubsidiary of SOLUTIA Inc., Dietenheim, Germany.

SR-833S: tricyclodecane dimethanol diacrylate available from SartomerUSA, LLC, Exton, Pa.

Madico tape: back-sheet film commercially available under the tradedesignation “TAPE” from Madico, Woburn, Mass.

N-n-butyl-aza-2,2-dimethoxysilacyclopentane was obtained from Gelest,Inc., Morrisville, Pa. under the trade name “Cyclic AZA Silane 1932.4.”

T-Peel Test Method

Films having a barrier coating were cut to 20 cm (8 inch)×30.5 cm (12inch) rectangular sections. These sections were then placed into alaminate construction containing a bottom back-sheet (Madico tape), asheet of ETIMEX 496.10 adjacent to the back-sheet, and the barrier filmon top of the EVA sheet with the barrier coating oriented towards theEVA encapsulant. The construction was laminated at 150° C. for 12minutes and 10⁵ Pa (1 atm) of pressure. Two pieces of plastic materialabout 25 mm wide by 20 cm long were placed between the barrier film andthe EVA layer along both 20 cm long edges to form unbonded edges. Theresulting laminate was then cut into 25 mm wide×152 mm long strips suchthat one end contained the 25 mm unbonded ends that were to be placed inthe clamping grips of the test machine. The two unbonded ends of filmwere placed in a tension testing machine according to ASTM D1876-08“Standard Test Method for Peel Resistance of Adhesives (T-Peel Test).” Agrip distance of 12.7 mm was used and a peel speed of 254 mm/min (10inches/min) was used. T-Peel testing was completed according to ASTMD1876-08 except where otherwise stated. The peak peel force was measuredfor three samples and averaged to produce the results.

Comparative Example C-1

An ethylene tetra fluoro ethylene (ETFE) substrate film was covered witha stack of an acrylate smoothing layer, an inorganic silicon aluminumoxide (SiAlOx) barrier layer, a Silicon Oxide (SiOx) layer, an acrylateprotective layer, and a second inorganic barrier layer. Barrierassemblies were made on a vacuum coater similar to the coater describedin U.S. Pat. No. 5,440,446 (Shaw et al.) and U.S. Pat. No. 7,018,713(Padiyath, et al.). The individual layers were formed as follows:

(Layer 1—smoothing polymeric layer.) A 350 meter long roll of 0.127 mmthick×366 mm wide ETFE film was loaded into a roll-to-roll vacuumprocessing chamber. The chamber was pumped down to a pressure of 1×10⁻⁵Torr. The web speed was maintained at 3.7 meters/min while maintainingthe backside of the film in contact with a coating drum chilled to −10°C. With the film in contact with the drum, the film surface was treatedwith a nitrogen plasma at 0.05 kW of plasma power. The film surface wasthen coated with tricyclodecane dimethanol diacrylate (SR-833S). Thediacrylate was vacuum degassed to a pressure of 20 mTorr prior tocoating, and pumped at a flow rate of 1.0 mL/min through an ultrasonicatomizer operated at a frequency of 60 kHz. A flow of 10 standard cubiccentimeters per minute (sccm) of nitrogen gas heated to 100° C. wasadded concentrically to the diacrylate within the ultrasonic atomizer.The diacrylate and gas mixture was introduced into a heated vaporizationchamber maintained at 260° C. along with an additional 25 sccm of heatednitrogen gas. The resulting monomer vapor stream condensed onto the filmsurface and was electron beam crosslinked using a multi-filamentelectron-beam cure gun operated at 9.0 kV and 3.1 mA to form a 720 nmacrylate layer.

(Layer 2—inorganic layer.) Immediately after the acrylate deposition andwith the film still in contact with the drum, a SiAlOx layer wassputter-deposited atop a 350 meter length of the acrylate-coated websurface. Two alternating current (AC) power supplies were used tocontrol two pairs of cathodes, with each cathode housing two 90% Si/10%Al targets. During sputter deposition, the voltage signal from eachpower supply was used as an input for aproportional-integral-differential control loop to maintain apredetermined oxygen flow to each cathode. The AC power suppliessputtered the 90% Si/10% Al targets using 3500 watts of power, with agas mixture containing 850 standard cubic centimeters per minute (sccm)argon and 63 sccm oxygen at a sputter pressure of 3.5 mTorr. Thisprovided a 30 nm thick SiAlOx layer deposited atop the Layer 1 acrylate.

(Layer 3—inorganic layer.) Immediately after the SiAlOx deposition andwith the film still in contact with the drum, a sub-oxide of silicon(SiOx, where x<2) tie-layer was sputter deposited atop the same 350meter length of the SiAlOx and acrylate coated web surface using a99.999% Si target. The SiOx was sputtered using 1000 watts of power,with a gas mixture containing 200 sccm argon and 10 sccm oxygen at asputter pressure of 1.5 mTorr, to provide a SiOx layer approximately 3to 6 nm thick atop Layer 2.

(Layer 4—protective polymeric layer.) Immediately after the SiOx layerdeposition and with the film still in contact with the drum, a secondacrylate (same acrylate as in Layer 1) was coated and crosslinked on thesame 350 meter web length using the same general conditions as for Layer1, but with these exceptions. Electron beam crosslinking was carried outusing a multi-filament electron-beam cure gun operated at 9 kV and 0.40mA. This provided a 720 nm acrylate layer atop Layer 3.

(Layer 5-inorganic layer.) In a separate reverse pass through theroll-to-roll vacuum processing chamber and with the web moving at 3.7meters/minute, a second SiAlOx (same inorganic as in layer 3) wassputter deposited atop the same 350 meter web length using the sameconditions as for Layer 3. This provided a 30 nm thick SiAlOx layerdeposited atop the Layer 4 protective acrylate layer.

The resulting five layer stack on the polymeric substrate exhibited anaverage spectral transmission Tvis=92% (determined by averaging thepercent transmission between 400 nm and 700 nm) measured at a 0° angleof incidence. A water vapor transmission rate was measured in accordancewith ASTM F-1249 at 50° C. and 100% RH and the result was below the0.005 g/m²/day lower detection limit rate of the MOCON PERMATRAN-W®Model 700 WVTR testing system (commercially available from MOCON, Inc.,Minneapolis, Minn.).

T-peel tests were performed as described under T-Peel Test Method. Theinitial averaged peak adhesion T-peel pull force was 1.9 N/cm (1.1lbf/inch). The T-peel test results are summarized in Table 1.

Example 1—Barrier stack made withN-n-butyl-aza-2,2-dimethoxysilacyclopentane

An ethylene tetra fluoro ethylene (ETFE) substrate film was covered witha stack of an acrylate smoothing layer, an inorganic silicon aluminumoxide (SiAlOx) barrier layer, a protective layer made from an acrylateformulation containing SR-833S andN-n-butyl-aza-2,2-dimethoxysilacyclopentane, and a second inorganicbarrier layer. Barrier assemblies were made on a vacuum coater similarto the coater described in U.S. Pat. No. 5,440,446 (Shaw et al.) andU.S. Pat. No. 7,018,713 (Padiyath, et al.). The individual layers wereformed as follows.

(Layer 1—smoothing polymeric layer.) A roll of 0.127 mm thick×366 mmwide ETFE film was loaded into a roll-to-roll vacuum processing chamber.The chamber was pumped down to a pressure of 1×10⁻⁵ Torr. The web speedwas maintained at 3.7 meters/min while maintaining the backside of thefilm in contact with a coating drum chilled to −10° C. With the film incontact with the drum, the film surface was treated with a nitrogenplasma at 0.05 kW of plasma power. The film surface was then coated witha tricyclodecane dimethanol diacrylate (SR-833S). The diacrylate wasvacuum degassed to a pressure of 20 mTorr prior to coating, and pumpedat a flow rate of 1.0 mL/min through an ultrasonic atomizer operated ata frequency of 60 kHz. A flow of 10 standard cubic centimeters perminute (sccm) of nitrogen gas heated to 100° C. was added concentricallyto the diacrylate within the ultrasonic atomizer. The diacrylate and gasmixture was introduced into a heated vaporization chamber maintained at260° C. along with an additional 25 sccm of heated nitrogen gas. Theresulting monomer vapor stream condensed onto the film surface and waselectron beam crosslinked using a mutli-filament electron beam cure gunoperated at 9.0 kV and 3.1 mA to form a 720 nm acrylate layer.

(Layer 2—inorganic layer.) Immediately after the acrylate deposition andwith the film still in contact with the drum, a SiAlOx layer wassputter-deposited atop a 20 meter length of the acrylate-coated websurface. Two alternating current (AC) power supplies were used tocontrol two pairs of cathodes, with each cathode housing two 90% Si/10%Al targets. During sputter deposition, the voltage signal from eachpower supply was used as an input for aproportional-integral-differential control loop to maintain apredetermined oxygen flow to each cathode. The AC power suppliessputtered the 90% Si/10% Al targets using 3500 watts of power, with agas mixture containing 850 sccm argon and 82 sccm oxygen at a sputterpressure of 3.7 mTorr. This provided a 30 nm thick SiAlOx layerdeposited atop the Layer 1 acrylate.

(Layer 3—protective polymeric layer.) Immediately after the SiAlOx layerdeposition and with the film still in contact with the drum, a secondacrylate containing N-n-butyl-aza-2,2-dimethoxysilacyclopentane loadedto 3% into the SR-833S was coated and crosslinked on the same 20 meterweb length using the same general conditions as for Layer 1, but withthese exceptions. The SR-833S was degassed as in layer one (above) andthen before loading into the delivery syringe a 1.5 g (3% by weight) ofN-n-butyl-aza-2,2-dimethoxysilacyclopentane was thoroughly stirred inprior to evaporating the formulation. Electron beam crosslinking wascarried out using a multi-filament electron-beam cure gun operated at 9kV and 0.40 mA. This provided a 720 nm acrylate layer atop Layer 3.

(Layer 4—inorganic layer.) In a separate pass through the roll-to-rollvacuum processing chamber and with the web at 3.7 meters/minute, asecond SiAlOx (same inorganic as in layer 3) was sputter deposited atopthe same 350 meter web length using the same conditions as for Layer 3.This provided a 30 nm thick SiAlOx layer deposited atop the Layer 3protective acrylate layer.

The resulting four layer stack on the polymeric substrate exhibited anaverage spectral transmission Tvis=92% (determined by averaging thepercent transmission between 400 nm and 700 nm) measured at a 0° angleof incidence. A water vapor transmission rate was measured in accordancewith ASTM F-1249 at 50° C. and 100% RH and the result was below the0.005 g/m²/day lower detection limit rate of the MOCON PERMATRAN-W®Model 700 WVTR testing system (commercially available from MOCON, Inc,Minneapolis, Minn.).

T-peel tests were performed as described under T-Peel Test Method. Theinitial averaged peak adhesion T-peel pull force was 35.0 N/cm (20.0lbf/inch). Additional samples were placed into an environmental chamberheld at constant temperature of 85° C. and constant 85% relativehumidity and aged for 100 and 250 hours. After 100 hours, the averagedpeak T-peel measurements were made and the averaged peak adhesion valuewas 37.1 N/cm (21.2 lbf/in). The resulting averaged peak peel strengthafter 250 hours was 33.6 N/cm (19.2 lbf/in). The T-peel test results aresummarized in Table 1.

TABLE 1 Initial Peak Peel Peak Peel Force Peak Peel Force Example Force(N/cm) after 100 hr (N/cm) after 250 hr (N/cm) C-1 1.9 — — 1 35.0 37.133.6

What is claimed is:
 1. A barrier film, comprising: a substrate; a basepolymer layer applied to the substrate; an oxide layer applied to thebase polymer layer; and a top coat polymer layer applied to the oxidelayer, wherein the top coat polymer layer comprises a reaction productof a cyclic aza-silane, an acrylate monomer having a molecular weight ina range of about 150 to about 600 grams per mole, and a surface of theoxide layer.
 2. The barrier film of claim 1, further comprising aplurality of alternating layers of the base polymer layer and the oxidelayer between the substrate and the top coat polymer layer.
 3. Thebarrier film of claim 1, wherein the substrate comprises a flexibletransparent film.
 4. The barrier film of claim 1, wherein the basepolymer layer comprises an acrylate smoothing layer.
 5. The barrier filmof claim 1, wherein the oxide layer comprises a layer of an inorganicsilicon aluminum oxide.
 6. The barrier film of claim 1, furthercomprising an inorganic layer applied to the top coat polymer layer. 7.The barrier film of claim 6, wherein the inorganic layer comprises alayer of an inorganic silicon aluminum oxide.
 8. The barrier film ofclaim 1, wherein the acrylate monomer has a molecular weight from about200 to about 400 grams per mole.
 9. The barrier film of claim 1, whereinthe acrylate monomer is tricyclodecane dimethanol diacrylate.
 10. Thebarrier film of claim 1, wherein the cyclic aza-silane isN-n-butyl-aza-2,2-dimethoxysilacyclopentane.